KR960005641B1 - Apparatus of detection for fuel level - Google Patents

Abstract

The apparatus, detecting the level of the fuel in automobiles, boilers or industrial equipments, has a structure easy to assemble, prevents malfunction caused by the flow of the fuel, and reduces the consumption of the electric power. It comprises a level detector(10) including serially-connected NTC(negative temperature coefficient) thermisters(18) sensing the resistor variation according to the change of the fuel level; a heating plate case(15) having a guide groove(16) for the detector(10) to be fixedly inserted into; a constant temperature heater(11) regulating the temperature of the detector(10) in order not to be affected by the external temperature by use of a heating wire(13) and a constant temperature unit(14); a fule flow checker(12) preventing the wrong operation of the detector(10).

Description

Fuel level detector

1 is a schematic diagram showing a conventional fuel level detecting device.

2 is a perspective view showing a fuel level detecting device of the present invention.

3 is an internal configuration diagram of a constant temperature heating unit according to the present invention.

4 is an internal configuration diagram of a fuel level detection unit according to the present invention.

5 is an exploded perspective view for explaining the interaction between the constant temperature heating unit and the fuel level detection unit according to the present invention.

Figure 6 is a perspective view showing the appearance of the fuel flow preventing unit according to the present invention,

7 is a graph showing temperature-resistance characteristics of a negative temperature coefficient (NTC) thermistor applied to the present invention.

8 is a graph showing the fuel level-resistance characteristics of the NTC thermistor according to the present invention.

* Explanation of symbols for main parts of the drawings

1: power supply unit 2: power supply device

3: constant voltage unit 4: fuel level guide needle

5: bimetal 6: resistance coil

7: Knitted 8: Contact arm

9: fuel gauge substrate 10: fuel level detection unit

11: constant temperature heating part 12: fuel flow prevention part

13 heating line 14 constant temperature element

15: heating plate case 16: guide groove

17: junction 18: NTC thermistor

19: printed electrode 20: constant temperature heating plate

21: fuel flow prevention case 22: fuel entry and exit

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel level detecting device for detecting fuel levels in a fuel tank in home or industrial equipment in which fuel tanks such as automobiles, boilers, hot air fans, or industrial cutting oil are used.

Conventionally, as shown in FIG. 1, a float (7), a resistance coil (6), a contact arm (8), and a bimetal (5) are described.

When the user turns on the power supply switch 2 to detect the fuel amount, the supply current of the power supply unit 1 flows through the constant voltage unit 3 to the bimetal 5 connected to the fuel level guide needle 4 once, The other end flows through the resistance coil 6.

At this time, if the position of the floater 7 is moved up and down by the amount of fuel, the contact arm 8 which operates in conjunction with this is moved to the left and right of the resistance coil 6 to be in contact with it.

Accordingly, the resistance value of the resistance coil 6 is changed according to the contact position of the resistance coil 6, and thus the amount of supply current supplied to the bimetal 5 is changed, so that the fuel amount guide needle 4 is floated ( When 7) goes down, it points in the direction of the point E of the fuel gauge substrate 9, and when the float 7 rises, it points in the direction of the point F of the fuel gauge substrate 9.

However, the fuel level detection device operating as described above causes the float to move due to the flow of fuel, causing the needle of the fuel gauge substrate to malfunction, the power consumption by the bimetal and the resistance coil to be large, and the structure to be complicated. This led to an increase in the cost of the product.

The present invention has been made in view of the above-mentioned conventional problems, and its object is to make the structure small and light, to be easy to assemble and install during manufacture, to prevent malfunction due to the flow of fuel, and to consume It is to provide a fuel level detection device to reduce the power.

In order to achieve these, a fuel level detection unit for connecting n NTC thermistors in series to measure the fuel level by the resistance change according to the fuel amount, and a constant temperature at which the fuel level detection unit maintains a constant temperature so as not to be affected by the ambient temperature change. The heating unit and the fuel level detection unit is characterized in that the fuel flow prevention portion for preventing the flow of the fuel so as not to malfunction by the fuel flow.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

FIG. 2 shows the fuel level detecting device of the present invention, wherein the fuel level detecting device 10 is disposed in the center, and the constant temperature heating unit keeps the fuel level detecting device 10 from being affected by the change in ambient temperature. (11) and the fuel flow prevention part 12 which prevents the flow of fuel are joined to both sides of the said fuel level detection part 10. As shown in FIG.

3 shows the internal configuration of the constant temperature heating unit 11 according to the present invention, which is composed of a heating element 13, a thermoelectric element 14 such as a PTC thermistor or a thermal ferrite element, and a heating plate case 15. When the power supply switch 2 is turned on, the current of the power supply unit 1 is supplied through the heating line 13 and the constant temperature element 14 to generate heat.

At this time, when the predetermined temperature is reached, the current is cut off by the characteristics of the thermostat, and when the temperature falls below the predetermined temperature, the current is energized again to maintain the constant temperature.

4 is a diagram illustrating an internal configuration of the fuel level detecting unit 10 according to the present invention, in which the n NTC thermistors 18 are energized with each other in the longitudinal direction through each of the printed electrodes 19 of the constant temperature heating plate 20. The n NTC thermistors 18 are configured to be connected in series and, when applied as a power source of the power supply unit 1, generate heat with predetermined resistance values.

FIG. 5 is a diagram illustrating the interaction between the constant temperature heating unit 11 and the fuel level detecting device 10 according to the present invention, and guides the left and right sides of the heating plate case 15 of the constant temperature heating unit 11. The constant temperature heating plate 20 of the fuel level detecting device 10 is slide-mounted and sealed through the groove 16 to prevent the heating line 13 and the constant temperature element 14 from being directly in contact with the fuel. The n NTC thermistors 18 of the level detection unit 10 face each other and are spaced apart at predetermined intervals from the smoke line 13 in the heating plate case 15, and each of the printed electrodes positioned opposite to the NTC thermistor 18 ( 19) is configured to be in contact with the fuel.

6 is a view illustrating an outer shape of the fuel flow preventing part 12 according to the present invention, wherein the fuel flow preventing case 21 is formed in a rectangular box shape having an open front face, and a plurality of fuel flow prevention cases 21 are vertically located at the center of the rear face. The fuel entrance hole 22 is formed, and the front surface is opened so that the constant temperature heating portion 11 is joined to the junction portion 17 so that the fuel flow prevention case through the fuel entrance hole 22 even though the external fuel flows ( The fuel introduced in 21 is not flowed.

7 shows the temperature-resistance characteristics of the NTC thermistor 18 applied to the present invention. The NTC thermistor is a thermosensitive resistor whose resistance in the device decreases exponentially with increasing temperature. It generates heat to maintain a high temperature and at the same time maintains low resistance.

8 shows the fuel level-resistance characteristics of the NTC thermistor 18 according to the present invention. When 10 NTC thermistors 18 are applied to the fuel level detecting unit 10 and a power supply voltage is applied to 12 V, It is shown that the fuel level changes in accordance with the resistance value of the fuel level detection unit 10.

Referring to the operation and effects of the present invention as described above are as follows.

When the current is supplied to the n NTC thermistors 18 of the fuel level detecting unit 10, the resistance value of each NTC thermistor 18 is about 10 Ω at a temperature of 40 ° C, and the achieved temperature is 1 Ω or less at 200-250 ° C. Will have characteristics.

When the fuel level detection unit 10 composed of n NTC thermistors 18 having these characteristics is mounted in the fuel tank (not shown), the summation resistance values of the parts immersed in the fuel and the parts not immersed are changed according to the fuel level. do.

For example, when there are ten NTC thermistors 18 of the fuel level detection unit 10 mounted in the fuel tank, when all ten NTC thermistors 18 are positioned below the level of the fuel, the cooling effect by the fuel This prevents thermistors 18 from generating heat.

Therefore, the resistance value of each NTC thermistor 18 becomes 10 Ω by the temperature-resistance characteristic of the NTC thermistor 18, and the resistance value of each NTC thermistor 18 adds up to 100%.

In addition, when only nine NTC thermistors 18 are positioned below the fuel level, and only one NTC thermistor 18 is exposed above the fuel level, the temperature-resistance characteristics of the NTC thermistors 18 lie below the level. The total resistance value of the nine NTC thermistors 18 is 90?, And the exposed one NTC thermistor 18 is in a high temperature state due to heat generation and has a value of 1?

If eight NTC thermistors 18 are located below the fuel level and only two NTC thermistors 18 are exposed above the fuel level, the summation resistance of the eight NTC thermistors 18 lying below the level will be 80Ω, the combined resistance value of the two exposed NTC thermistors 18 is 2Ω, and the total resistance is 82Ω.

As mentioned above, the value which NTC thermistor 18 changes according to fuel level is specified in following Table 1.

TABLE 1

According to each resistance value of (Table 1) above The current value can be calculated by the formula

The amount of fuel can be determined by moving the guide needle of the instrument panel by the calculated current value.

In this case, the constant temperature heating unit 11 constantly adjusts the fuel level detection unit 10 to a predetermined temperature (about 40 ° C.) in order to prevent the resistance value of the fuel level detection unit 10 from changing due to a change in the ambient temperature of the season. Heat it.

In addition, the fuel flow prevention unit 12 is mounted so that the resistance value of the fuel level detection unit 10 does not change due to the fluctuation of the fuel.

As described above, the present invention provides a fuel level detector for measuring a fuel level based on a resistance change value of the NTC thermistor by connecting a small and lightweight NTC thermistor element in series, and the fuel level detector affected by the change in ambient temperature. By adopting a constant temperature heating unit which prevents it from receiving, and a fuel flow preventing unit that prevents the fuel level detecting unit from malfunctioning due to fuel flow, the structure can be made compact and lightweight, and it is easy to assemble and install during manufacturing, and also fuel It can prevent the operation by the flow, can provide a useful effect to reduce the power consumption.

Claims (6)

In the fuel level detection unit, n NTC thermistors 18 are connected in series to guide the fuel level detection unit 10 and the fuel level detection unit 10 to insert and fix the fuel level by measuring the fuel level according to the amount of resistance change according to the fuel amount. The power supply 1 is composed of a heating plate case 15 having a groove 16 and a heating line 13 and a constant temperature element 14 fixed to the heating plate case 15 and connected in series to the power supply 1. When the heating line 13 generates heat and reaches a predetermined temperature, the power source 1 is cut off by the thermostat element 14 so that the fuel level detecting unit 10 is not affected by the change in ambient temperature. A fuel level detecting device comprising a constant temperature heating unit 11 for maintaining a temperature and a fuel flow preventing unit 12 for preventing the flow of fuel so that the fuel level detecting unit 10 does not malfunction due to fuel flow. . The method of claim 1, wherein the fuel level detecting unit 10 is characterized in that the n NTC thermistors 18 are connected in series in the vertical direction through each of the printed electrodes 19 of the constant temperature heating plate 20 so as to energize each other. Fuel level detector. The fuel level detection device according to claim 2, wherein the NTC thermistor (18) has a resistance value of 10Ω at a temperature of 40 ° C and a resistance value of about 1Ω at a temperature of 200-250 ° C. The fuel level detection device according to claim 1 or 2, wherein n is 10. The fuel level detection device according to claim 1, wherein the thermostat device (14) comprises a PTC thermistor or a thermosensitive ferrite element. According to claim 1, wherein the interlocking prevention portion 12 is formed in a rectangular box having a front opening is formed in the shape of a plurality of fuel entry and exit 22 in the longitudinal direction in the center of the rear surface of the constant temperature heating unit ( A fuel level detection device, characterized in that made to be bonded to the junction of 11).